/*
 * Copyright 2006 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.sample.kitchensink.client;

import com.google.gwt.user.client.ui.Composite;

/**
 * A 'sink' is a single panel of the kitchen sink. They are meant to be lazily
 * instantiated so that the application doesn't pay for all of them on startup.
 */
public abstract class Sink extends Composite
{

    /**
     * Encapsulated information about a sink. Each sink is expected to have a
     * static <code>init()</code> method that will be called by the kitchen sink
     * on startup.
     */
    public abstract static class SinkInfo
    {
        private Sink instance;
        private String name, description;

        public SinkInfo(String name, String desc)
        {
            this.name = name;
            description = desc;
        }

        public abstract Sink createInstance();

        public String getDescription()
        {
            return description;
        }

        public final Sink getInstance()
        {
            if (instance != null)
                return instance;
            return (instance = createInstance());
        }

        public String getName()
        {
            return name;
        }
    }

    /**
     * Called just before this sink is hidden.
     */
    public void onHide()
    {
    }

    /**
     * Called just after this sink is shown.
     */
    public void onShow()
    {
    }
}
